Variable Rate Front Coil Spring Box for Ford Super Duty 4WD

About this part

Variable Rate Front Coil Spring Box, fitment-checked

Variable rate front coil springs, which stiffen progressively as they compress rather than running one rate throughout. The truck stays compliant unloaded and firms up under weight. Supplied against kit F17852K. Note this part supersedes an earlier number.

A variable rate spring changes its resistance through the stroke, which is why a Super Duty fitted with them can ride acceptably empty and still support a load without wallowing. This box carries the front springs for kit F17852K, covering the 2005-2018 F-250 and F-350 Super Duty in 4WD across Cabela's, King Ranch and the Harley-Davidson Edition. Skyjacker records it as superseding part number F545, so older documentation may name the earlier one. 60.5 lb boxed.